Humectants or moisture stabilizers are used in the manufacture of foodstuffs and industrial products in order to prevent the products drying out. Another principal area of application for these moisture stabilizers is skin care products for keeping the skin moist and supple. The surface of the human skin, the epidermis, contains natural moisture regulators. These moisture regulators--known as Natural Moisturising Factors NMF--are described in detail in the relevant literature, e.g. Rompp Chemie Lexikon 9th edition (1990) Vol.2, p. 1347, and consists of 40% free amino acids, 12% L-2-pyrrolidone-5-carboxylic acid, 12% lactate, 7% urea, 1.5% uric acid, glucosamine, keratin, ammonium, sodium, potassium, magnesium and calcium citrates, formates, phosphates and chlorides.
In addition to the moisture-regulating effect, the organic acids also exercise a protective function for the skin, since they form a natural acidic mantle. These natural humectant substances are dissolved out by soaps or other surfactants, and the result is drying out and scaling off of the skin. These natural moisture regulators are meant to be replaced in skin care products by synthetic humectants such as glycols, glycerine or hydrolysates of keratin or collagen-containing substances.
It would be desirable, however, at least as an alternative to the synthetic humectants, to obtain also natural humectants or possibilities possessing the identical or a similar chemical composition to the natural humectants.
In an article by Klaus Hoffmann, "Lactil--a new humectant complex", in: Seifen-Ole-Fette-Wachs 103 (1977), 7, the importance of 2-pyrrolidone-5-carboxylic acid as a natural substance peculiar to the skin is emphasized and proposed for use in hydroregulative cosmetics. A problem area is still the obtaining of suitable humectants from natural products.